Sources said investigators have narrowed down their investigation to the RM305 million payment to companies appointed to carry out studies for the Penang government.

The source added that investigators have recorded statements from witnesses in the companies concerned to identify the payment process.

"By poring over the documents seized in the course of investigation, we believe it will help us to identify whether the payment of RM305 million is the actual amount or has been increased.

"Investigators are also probing if the companies appointed to carry out the studies have the necessary credentials.

"Investigators are also establishing whether the experts appointed to carry out the studies have the necessary expertise, irrespective of whether they are from the government or private companies," the source noted.

It is learnt that the government has set certain standards for those carrying out studies, including feasibility studies for the undersea tunnel project.

Azam, when contacted, said they were specifically looking into payment to the companies appointed to carry out the studies.

He added that as it involved techical aspects, investigators needed more time to investigate the matter.

"As such, we appreciate if we are given the space and chance to carry out investigation to the best of our ability.

"We are still recording statements from important witnesses, whom we believe can assist in our investigation.

"We will be calling several key figures soon to have their statements recorded," he added.

On Tuesday, the MACC raided four state agencies and three companies, and arrested two company directors, with the title Datuk, to assist in its probe.

Yesterday, the graft buster raided another 12 premises in Penang and Kuala Lumpur. About 12 statements were recorded from witnesses.

Yesterday, Chief Minister Lim Guan Eng told newsmen that the Penang government has not paid a single sen for the feasibility studies of the tunnel project, stressing that they had only paid by land swap for the three paired roads project.

He had said that the RM208 million land swap was for the environmental impact assessment (EIA) of the three paired roads projects.

Lim had also cried "political witch hunt" in the latest raid by the MACC.

The 7.2km undersea tunnel, which was awarded to Consortium Zenith, was part of a RM6.3 billion project, which also included the three paired roads.

The feasibility studies for the tunnel has been delayed for 21 months, and in October last year, Consortium Zenith claimed there was no hurry to complete the studies as the project was only expected to begin in 2023.